The faimly tree

While looking at the Black faimly tapestry with Sirius and Harry, Hermione notices that Regulus had a son. Sirius is shocked and at first wnats nothing to do with him, but evently he and some other members of the order go to meet him. Can they trust this Klaus and the rest of his mest up faimly and will they help defeat Voldemort. AU set during OOTP Fem!Regulus, Black faimly bonding